Effect of red palm weevil, Rhynchophorus ferrugineus (Olivier) infestation on temperature profiles of date palm tree

Abstract

This study aimed at identifying the impact of red palm weevil (RPW), Rhynchophorus ferrugineus Olivier infestation on date palm trees (Phoenix dactylifera) in terms of internal temperature changes compared to ambient atmospheric air temperature. Adult weevils as well as sensors of electronic data loggers were introduced inside date palm trees through holes drilled in the tree trunks for measuring internal temperatures at eight levels of infestation period (one to eight weeks). Three levels of forced infestation were used: 1 male: 1 female, 1 male: 2 females, and 2 males: 4 females. A group of date palm trees with only logger's sensors inside were used as a control. Four loggers with their sensors were hung outside on the date palm trees to measure ambient air temperatures during the experiment. Both minimum and maximum temperatures of healthy (uninfested) and infested date palm trees fell within ranges that were always above the minimum and below the maximum ambient temperature for the whole duration of the experiment. The average temperature of infested date palm (32.60°C) was significantly higher than the average temperature recorded at the same time both inside the healthy trees (29.53°C) and in the ambient atmosphere (29.35°C). The average temperature of infested date palm increased slightly with increase in infestation level with the highest being 32.80°C, which was recorded inside date palm infested with 2 males and 4 females, while it was 32.54 and 32.45°C inside trees infested with 1 male and 1 female, and 1 male and 2 females, respectively. It is evident that temperature differences between infested date palm on one side and healthy date palm and ambient atmosphere on the other side could well provide a platform for identifying infested trees. This is a valuable baseline information for further research to develop a real time multi-sensor fusion system for an effective early detection of RPW infestation which is a crucial step in the implementation of successful RPW integrated pest management (RPW-IPM) programs. Key words: Rhynchophorus ferrugineus, date palm, forced infestation, electronic data loggers, temperature profiles, red palm weevil (RPW) early detection.